What quote from Their Eyes Were Watching God shows that this novel is reflective of the 1920s?
In Chapter 5, there is a passage in which Janie is told by Jody to "mind the store." Here we can see several aspects of African American culture in the 1920s: the mercantile, the clientel, and the fashions:
Before the store had a complete roof, Jody had canned goods piled on the floor and was selling so much that he didn't have time to go off on his talking tours. She had her first taste of presiding over it the day it was complete and finished. Jody told her to dress up and stand in the store all evening. Everybody was coming sort of fixed up, and he didn't mean for nobody else's wife to rank with her...So she put on one of her bought dresses...Her silken ruffles rustled and muttered about her. The other women had on percale and calico with here and there a head-rag among the older ones.
During the previous four chapters, there are many remembrances of slave life by Janie's grandmother, but now, fortunes and opportunities have opened up for African Americans(though not nearly as much as possible... that would take almost another fifty years).
Note also that "store bought" dresses were beginning to come into vogue for all races; calico and percale were popular prints. (Be aware too of how the fashionable youth are contrasted with their behind-the-times elders.)